JPS6316634B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an insulator having a through hole in the center, which is used, for example, to penetrate the wall surface of a metal airtight container or to install it in the middle of a metal pipe to ensure insulation. This relates to pipe fittings. Conventionally, it has been widely used as a part necessary for transporting liquid nitrogen, chlorofluorocarbons as a cooling medium, etc. However, since the voltage to be insulated for both is low, it is necessary to improve the insulation resistance or creepage resistance by targeting high voltage. No special consideration was given to them. Recently, it has been found buried underground in countries such as Canada and Venezuela. Regarding extracting oil from oil sand layers,
Two electrodes are buried in an oil sand layer approximately 500 meters underground, and a voltage is applied between the two electrodes to raise the temperature of the oil sand layer using Joule heat and reduce the viscosity of the oil contained therein. A method of extracting only the oil from the ground is being seriously considered.

In this case, the voltage applied between the two poles is generally 4000
~5000V high voltage. However, since the resistivity of the upper stratum may be lower than the resistivity of the oil sand layer, it is necessary to insert an insulated pipe joint between the steel pipe buried in the stratum and the electrode buried in the oil sand layer. be. If an insulated pipe joint is not used, the current will flow to the underground layer and concentrate between the electrodes buried in the target oil sand layer, and the current will no longer flow. As a result, demand for insulated pipe joints has rapidly increased.

The main characteristics required of insulated pipe joints used for the above purpose are as follows. Since the electrode is held suspended, it has high mechanical strength, and since a voltage of 4000 to 5000 V is applied to one end of the electrode and it is necessary to maintain insulation from the steel pipe at the other end, it maintains high withstand voltage characteristics including creepage insulation resistance. In addition to maintaining the mechanical and electrical properties mentioned above at high temperatures, as the temperature rises due to electricity flowing between the electrodes, it also has excellent cold and thermal shock resistance, and since contact with the hole wall inevitably occurs during burial, the mechanical The central through hole is equal to the inner diameter of the upper steel pipe and electrode, and the flow resistance is low. It maintains a high degree of airtightness under the above conditions, and has long-term reliability without aging. In addition, it can be easily connected to the upper and lower steel pipes and electrode parts.

In the case of this type of insulated pipe joint, the basic structure is a structure in which an insulator is interposed between two conduits. Insulators have the greatest influence on the above-mentioned required characteristics.
This insulator will be explained below. When an organic material is used as an insulator, there is an unavoidable fatal flaw in that various properties rapidly deteriorate due to temperature rise, so it cannot be used in reality. Next, when using glass, due to sudden changes in temperature,
There are defects such as cracking and low mechanical impact strength.Also, when porcelain materials are used and sealed with low melting point metals or by shrink fitting, similar to glass materials, thermal and It has a fatal flaw of low mechanical impact strength,
These are also practically unusable. Insulators made of glass or mica plastics, which will be described in detail below, are the most excellent in terms of the above-mentioned properties.

Glass and mica plastics are made from a mixture of vitreous powder and mica powder, heated to a temperature at which the vitreous material softens and flows under pressure, and then pressure-molded in the heated state. It refers to the insulating material obtained.

Among the insulating pipe joints using glass or mica plastic bodies as insulators, the most ideal one that meets the conventionally required characteristics is the one previously proposed by the present inventors (Japanese Patent Application Laid-Open No. 147988/1983). The structure will be explained below with reference to FIG. 1A.

FIG. 1A is a vertical cross-sectional view showing the structure, in which 1 is a cylindrical first tubular member, and a first tube is inserted through a shoulder 1-1.
An outer peripheral fitting 3 having an inner diameter larger than the outer diameter of the tubular member 1.
Equipped with: A second tubular member 2 has the same inner and outer diameters as the first tubular member 1. All are made of metal that can withstand heating of around 600℃, including iron,
Stainless steel or the like is preferably used. The first and second tubular members 1 and 2 have spaces 4 and 4-1.
are held and supported, and these spaces 4 and 4-1
is filled with an insulating material 5 made of glass or mica plastic, which completely seals and fixes the first tubular member 1 and the second tubular member 2 and maintains insulation.
1a and 2a are connection parts to adjacent vessel walls or metal pipes, and are connected by an appropriate method such as welding or screwing. This insulated pipe fitting maintains its mechanical strength, cold shock resistance, mechanical shock strength, and airtightness even at high temperatures, has no unevenness in its through holes, has low flow resistance, and does not change over time. Although it maintains long-term reliability and is ideal, when used under high voltage conditions, it has fatal flaws in withstanding voltage characteristics and creeping insulation resistance characteristics. This relationship will be explained in detail below.

The mica powder used to produce the mica plastic body is in the form of flakes, and the ratio of average particle diameter to thickness of the flakes is generally 30 to 50:1. On the other hand, vitreous powder is in the form of fine powder with no directionality. When the above-mentioned mixed powder is heated to a temperature at which the vitreous material becomes soft and fluid, and then pressure-molded in the heated state, the mixed powder is pressed with almost no movement if the shape is plate-like. At this time, the mica flakes are arranged parallel to the pressurized surface, resembling a laminated product. Next, when the mixed powder is molded by applying pressure and being injected into the gap, the flowing parts are arranged parallel to the flow direction, and the parts that do not move and receive pressure are parallel to the pressing direction. It will be arranged. The state of this array is the first
It is shown in Figure B. As is clear from this, the arrangement direction differs depending on the position. That is, the glass and mica plastic bodies in the space 4 between the second tubular member 2 and the outer metal fitting 3 are arranged parallel to the flow direction, that is, parallel to the second tubular member 2, as shown in arrangement 6-2. The arrangement 6-1 is also parallel to the outer peripheral fitting 3. Since the array 6-5 is pressurized with almost no movement, it is parallel to the pressurizing surface, and is arranged at right angles to the second tubular member 2. Also, array 6-6 is
They are arranged parallel to the inner circumferential surface in order to receive pressurization after they have almost stopped moving.

Next, the relationship between the arrangement direction of mica flakes and mechanical and electrical properties will be explained. First, regarding mechanical strength, tensile strength is strong in the direction parallel to the alignment and extremely weak in the direction perpendicular to the alignment. Conversely, the direction perpendicular to the alignment is extremely strong in compression, but extremely weak in tension as it causes delamination. Therefore, when the thickness of a molded product reaches approximately 25 mm, stress generated on the surface and inside of a single molded product causes
In addition, in the case where metals are molded in contact with each other as shown in FIG. As described above, mechanical strength is largely controlled by the arrangement direction.
Next, regarding the relationship with electrical characteristics, the characteristics also vary greatly depending on the arrangement direction. In the direction perpendicular to the alignment direction, a withstand voltage of 15 to 20 KV/mm is maintained, but in the parallel direction, it is largely controlled by density. , which is extremely low.

Regarding the electrical characteristics of the insulated pipe joint, in FIG. Since they are arranged parallel to the second tubular member 2, the withstand voltage is extremely high and there is no problem at all. However, array 6-5 is the second
They are arranged perpendicularly to the tubular member 2 and have a low withstand voltage, and because they reach the outer metal fitting 3 through the layers, only an extremely low withstand voltage can be obtained. Next, regarding creeping insulation resistance, if mica flakes are arranged in layers as mentioned above, a thick molded product cannot be obtained, so arrangements 6-5 and 6-6 are naturally limited by the length. The maximum length is 20 to 25 mm. Under usage conditions where the surface is contaminated, creeping insulation resistance is extremely reduced.

As is clear from the above description, conventional insulated pipe joints cannot be used in applications where high voltage is applied.

The present inventors have made it possible to obtain a joint that can be used as an insulating pipe joint for oil sand extraction under conditions where high voltage is applied, for example, by determining the relationship between the arrangement direction of mica flakes and electrical properties. In addition to researching its structure, they also fundamentally examined its structure, and by considering the manufacturing method, succeeded in creating something that could fulfill the purpose.

The contents will be explained below with reference to FIG. FIG. 2A is a vertical sectional view showing the state after molding is completed and the arrangement of mica flakes, and FIG. 2B is a longitudinal sectional view showing the structure of the product after machining. To facilitate understanding, the manufacturing method will first be explained with reference to FIG. FIG. 3A is a vertical sectional view showing the state immediately before pressure forming, and FIG. 3B is a longitudinal sectional view showing the state after pressure forming is completed. In the figure, 1 is a cylindrical first tubular member, which has a cylindrical inner circumferential wall 1-1 facing the outer circumferential metal fitting 3 at one end, and a partition wall having an outer diameter equal to that of the inner circumferential wall 1-1 and a larger inner diameter at its tip. 1-2, and a ring-shaped support portion 1-3 for holding the second tubular member 2 is held at the inner peripheral portion of the inner peripheral wall 1-1. 2 is a second tubular member, the first tubular member 1
A cylindrical product with the same dimensions as the inner peripheral wall 1-1 of the first tubular member 1 at one end, and the inner peripheral wall 2-1 and the partition wall 2-2 with the same dimensions as the partition wall 1-2 and the first tubular member 1. The auxiliary wall 2-3 has an outer diameter that fits into the inner diameter of the inner peripheral wall 1-1. Reference numeral 3 denotes an outer circumferential metal fitting which is a cylindrical member whose inner diameter is larger than the outer diameter of the inner circumferential walls 1-1 and 2-1 so as to hold the space 4. At both ends, the first and second tubular members 1 and 2 are connected. It has a protective wall 3-1 that can hold the space 4. A metal fitting consisting of the three parts described above is used. As for the material, as with conventional products, any metal that can withstand heating of about 600 degrees Celsius is sufficient, and iron, stainless steel, etc. are preferably used.

For molding, a mold is used which is composed of four parts: a frame 7 shown in FIG. 3, a wall part 8 having a split structure and having a raw material chamber 8-1 on the upper part, a support metal 9, and a pressure metal 10. In the mold, the frame 7, wall 8, and support metal 9 are assembled as shown in FIG. 3A, and the pressure metal 10 is heated to a predetermined temperature without being roughened. a first tubular member 1;
The second tubular member 2 and the outer metal fitting 3 are also heated to a predetermined temperature, and the first tubular member 1 is first inserted into the support metal 9, and then the outer metal fitting 3 is placed on the support metal 9. and then insert the second tubular member 2 into the first tubular member 1.
Place it on the support part 1-3 of. Finally, the preform 11 of the raw material powder heated to a predetermined temperature is placed in the raw material chamber 8-
Insert into 1. The state at this time is shown in Figure 3A. Next, the preformed body 11 is pressurized by the pressurizing metal 10. The preform 11 flows and fills the space 4 formed by the first and second tubular members 1 and 2 and the outer metal fitting 3, and a portion remains in the raw material chamber 8-1 to form the insulator 5. . The state at this time is shown in FIG. FIG. 2A shows a molded product from which the mold is disassembled after cooling to a predetermined temperature and the molded product is taken out. The product is machined and finished as shown in Figure 2B.

The preformed body 11 used in the above molding is made from a mixed powder of mica powder (flakes) and glassy powder, and is made into a wet state by adding water, and then molded into a raw material chamber 8-1 using another mold (not shown). It is formed by cold pressing into a shape that can be filled into a container and dried to remove moisture.

Although the glass and mica flakes of the molded product molded by the above method are arranged as insulators, as shown in Figure 2A, most of the raw material powder has moved to the upper insulator 5-1. The mica flakes are arranged parallel to the pressurized surface because they are press-molded without any pressure. outer peripheral insulator 5-2 and sealing insulator 5-3,
In other words, the insulators in the cavities between the first and second tubular members and the third tubular member flow in the initial stage when the raw material powder is pressurized, and finally flow when the flow is almost completed. Since they are subjected to pressure, the mica flakes are arranged parallel to the wall surfaces of the first and second tubular members 1 and 2 and the outer peripheral fitting 3. Since the inner peripheral insulator 5-4 is also filled with flowing raw material powder, the mica flakes are arranged parallel to the walls of the partition walls 1-2, 2-2 and the spaces of the auxiliary wall 2-3. There is. Since the central part of the auxiliary wall 2-3 moves less, it is arranged perpendicularly or inclined to the wall surface. As mentioned above, the partition walls 1-2, 2-2 largely control the arrangement direction of the mica flakes, and if they were not present, most of the inner peripheral insulator 5-4 would be perpendicular to the auxiliary wall 2-3. It will be arranged.

Next, the protective wall 3-1 is necessary for supporting the outer peripheral metal fitting 3, and at the same time, the flowing preform 11 comes into contact with the mold wall 8, which is heated to a temperature lower than the heating temperature of the metal fitting. It plays a useful role in avoiding temperature drop and increase in flow resistance. Further, the reason why the outer diameter of the upper insulator 5-1 is made larger than the outer diameter of the outer peripheral fitting 3 is to increase the flow rate. The faster the flow rate is, the more easily the mica flakes are arranged in parallel to the flow direction. In addition, the time during which the flowing preform 11 is in contact with the low-temperature wall surface is short, the temperature does not drop, and the fluidity is good, so that the mica flakes are arranged in an orderly manner and are arranged parallel to the wall surface. At the same time, since the density of the molded product increases, the mechanical and electrical strength also improves, which is extremely useful for molding.

The above-mentioned molded article is finished into a product by machining as shown in FIG. 2B. In the case of this finished product, the sealing insulators 5-3 are arranged parallel to each wall surface between the first and second tubular members 1 and 2 and the outer peripheral fitting 3, and Since the partitions 1 and 2 are arranged so as to surround the partition walls 1-2 and 2-2, voltage is always applied at right angles to the mica flakes, so there is no problem with the withstand voltage characteristics.
Next, regarding the creeping insulation properties, the creeping insulation properties of the inner circumferential surface are such that the inner circumferential insulator 5-4 has mica flakes arranged parallel to the inner circumferential surface, so no cracks occur. Regarding its length, since the metal part located on the outer periphery is not a continuous integral part with the partition wall 2-2, there is less stress concentration applied to the inner peripheral insulator 5-4, and it is longer than conventional structural products. This eliminates the inability to construct long parts, which was a fatal flaw in conventional products. Regarding the creeping insulation characteristics of the outer circumferential surface, the outer circumferential insulator 5-2
are configured at both ends of the outer peripheral fitting 3, and
The mica flakes are arranged parallel to the first and second tubular members 1 and 2, and each can be configured to be longer than the conventional product, so the total creepage length is the same as the inner insulation length and is longer than the conventional product. defects have been completely eliminated.

Next, FIGS. 4 and 5 show an example of the structure of a product in which mechanical strength, especially the tensile strength of the first tubular member 1 and the second tubular member 2, is required to be extremely large. explain. First, in the case of FIG. 4, the inner peripheral walls 1 of the first and second tubular members 1 and 2
-1, 2-1 with a sloped surface on the outer periphery, and the inner peripheral wall 1-1, 2 on both ends 3-2 of the outer peripheral fitting.
Use one with a slope parallel to -1.
If the maximum diameter of the inner peripheral walls 1-1, 2-1 is configured to be smaller than the minimum diameter of both ends 3-2 of the outer peripheral metal fitting, molding can be carried out in exactly the same process as for the structural product shown in Fig. 2. be. In the case of this structural product, the tensile force applied to the first and second tubular members 1 and 2 is applied to the sloped surfaces of the inner peripheral walls 1-1 and 2-1 and both ends 3-
Since it is applied between the two sloped surfaces via the sealing insulator 5-3, its strength is greatly improved.

Next, in the case of FIG. 5, metal fittings provided with screws 1-4, 2-4 and 3-3 at both ends of the inner peripheral walls 1-1, 2-1 of the first and second tubular members and the outer peripheral metal fitting 3 are used. use. For molding, as shown in FIG. 5A, the parts are assembled by passing screws through them, and then inserted into a mold as an integral part. The rest can be molded by the same process as shown in FIG. In the case of this structure, the tensile force applied between the first and second tubular members 1, 2
Screws 1-4 and 2-4 and screw 3- of the outer metal fitting
3 through the sealing insulator 5-3. As mentioned above, glass and mica plastic bodies have extremely high compressive strength in the direction perpendicular to the mica flakes, and similar to general insulators, their compressive strength is extremely high, so their strength can be greatly improved.

The arrangement of mica flakes in the insulated pipe joint of the above example is shown in Figures 4A and 5A, and is almost similar to that shown in Figure 2A. As shown in Figure 4B and Figure 5B, the inner circumferential insulator 5-4 and the outer circumferential insulator 5
-2 is constructed as shown in FIG. 2(b), so that the electrical characteristics, including the creeping insulation resistance characteristics, are completely the same.

The insulated pipe joint of the present invention has the mechanical properties, mechanical and cold shock resistance, and
In addition to completely ensuring airtightness, no unevenness in the through holes, low flow resistance, and long-term reliability without aging, the withstand voltage characteristics and creeping insulation resistance characteristics, which were the fatal flaws of conventional products, are completely eliminated. removed and retains high characteristic values. Therefore, it can be used without any problems under conditions where high voltages are applied, which could not be used with conventional products.For example, as mentioned above,
It can now be effectively used for oil sand heating electrode parts and insulating pipe joints for steel pipes that need to maintain insulation properties when inserted into a 4000-5000V circuit, and its technical and practical effects are extremely large.

It should be noted that the secondary effect of improving mechanical strength by changing the structure of the metal fittings and converting the tensile force applied to the tubular member into compressive strength against the insulator is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing the structure of a conventional insulated pipe joint. FIG. 1A shows the structure, and FIG. 1B shows the arrangement of mica flakes. FIG. 2 is a longitudinal cross-sectional view showing the structure of the insulated pipe joint according to the present invention, and FIG.
Figure 2 (b) shows the structure of the product. FIG. 3 is a longitudinal cross-sectional view showing the method of forming the insulated pipe joint according to the present invention.
FIG. 3A shows the state immediately before pressure forming, and FIG. 3B shows the state after pressure forming is completed. 4 and 5 are longitudinal cross-sectional views showing the structure of other embodiments of the insulated pipe joint according to the present invention, and FIG. 4A and FIG. Figures 4(b) and 5(b) show the structure of the product. In the figure, 1 is a first tubular member, 2 is a second tubular member, 1-1, 2-1 is an inner peripheral wall as a cylinder, 1-
2, 2-2 are partition walls, 1-4, 2-4 are screws, 3 is an outer peripheral metal fitting as a third tubular member, 3-1 is a protective wall, 3-3 is a screw, 4 is a space, and 5 is a Insulator, 6
1 is an arrangement of mica flakes, 7 is a frame, 8 is a wall portion, 9 is a supporting metal, 10 is a pressurizing metal, and 11 is a preformed body.
In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A cylindrical body having the same inner and outer diameter dimensions, a cylindrical body connected to this cylindrical body and having an inner diameter equal to that of this cylindrical body, and a cylindrical body connected to this cylindrical body and having an inner diameter larger than that of this cylindrical body. first and second tubular members each consisting of a cylindrical partition wall that is large in size and has an equal or smaller outer diameter;
a third tubular member made of a cylindrical body having an inner diameter larger than the outer diameter of these tubular members; the first and second tubular members are held coaxially with their respective partition walls facing each other with a gap therebetween; A third tubular member is disposed on the outer periphery, and the spacing between the first and second tubular members, the hollow space between the first and second tubular members and the third tubular member, and the space between the first and second tubular members and the third tubular member are provided. A cylindrical insulator is provided on the outer periphery of the first and second tubular members in contact with the third tubular member for airtight sealing. It is a mica plastic body,
An insulated pipe joint characterized in that the mica flakes contained in the glass-mica plastic body are arranged parallel to the contact surfaces of the first and second tubular members. 2 The cylindrical bodies of the first and second tubular members have on their outer surfaces a conical sloped surface with the partition wall side as the bottom, and the third tubular member has on its inner surface an inverted conical shape with both ends as the bottom. The first and second tubular members are held coaxially with the partition walls facing each other with a gap between them, and the third tubular member has a sloped surface on the outer periphery of the first and second tubular members. The insulating pipe joint according to claim 1, wherein the insulating pipe joint is arranged so as to face the sloped surface of the second tubular member. 3 The cylindrical bodies of the first and second tubular members have screws on their outer surfaces, and hold a cylindrical portion adjacent to the screws with an outer diameter smaller than the root diameter of the screws and longer than the length of the screws. The third tubular member has a screw at both ends that is screwed into the screw, and has an inner diameter larger than the inner diameter of the screw, and the screw of the first and second tubular members is connected to the third tubular member. 2. The insulated pipe joint according to claim 1, wherein the insulated pipe joint is disposed so as to be penetrated by a screw.